diff --git a/src/Model/Extension/SeoPageExtension.php b/src/Model/Extension/SeoPageExtension.php
index 6e0fd6c..bad37af 100644
--- a/src/Model/Extension/SeoPageExtension.php
+++ b/src/Model/Extension/SeoPageExtension.php
@@ -273,9 +273,13 @@ public function updateSettingsFields(FieldList $fields)
     public function updateSummaryFields(&$fields)
     {
         if(Controller::curr() instanceof SEOAdmin) {
-            Config::modify()->set($this->owner->ClassName, 'summary_fields', $this->getSummaryFields());
+            if($this->owner->class == null){
+                return;
+            }
+            if(is_object($this->owner->class) && method_exists($this->owner->class, 'remove')) Config::inst()->remove(($this->owner->class), 'summary_fields');
+            Config::modify()->set(($this->owner->class), 'summary_fields', $this->getSummaryFields());
 
-            $fields = Config::inst()->get($this->owner->ClassName, 'summary_fields');
+            $fields = Config::inst()->get($this->owner->class, 'summary_fields');
         }
     }